“You discount the thousands in service”
Nope. They have provided an excellent platform. There is a reason why one rolls off the assembly line monthly. Technology advancment. Just as Pentium 1 computers became boat anchors. They are rapidly becoming outdated, but are also good for sale to foreign countries. And, apparently fit for target prctice for more advanced aircraft at Tyndall too.
The QF-16s are old A models that cannot be upgraded to current standards, and are being used as target drones because we're running out of flyable QF-4s.